propagate event between item in smartgwt

Hi
Technologies:
smartgwt3.0,gwt2.1,
IE9,
JDK6.22u.
I want when I click a buttonItem, another buttonItem is clicked autoamtically.
How attach the 2 events.
I try to resolve the problem using fireEvent, but I d'idn't understand very well the real function of this method